Freed from the Z Plan capsule, Gamera attacks a dam upon his return to Earth. Meanwhile, a private expedition to retrieve a rare opal in New Guinea unwittingly unleashes the malevolent Barugon. Virtually unstoppable and able to freeze anything in its path, the monstrous lizard turns modern cities into glaciers until Gamera arrives to challenge the marauder! But even the fire-spitting terrapin becomes trapped in the creatures frozen grip. Can one of the explorers, Keisuke Hirata (Kojiro Hongo, Satans Sword), and a New Guinea native, Karen (Kyoko Enami, The Woman Gambler), help to defeat Barugon before it plunges Japan into a new Ice Age?